Polymeric data carying devices are well-known and include identification cards, telephone calling cards, instant cash cards, credit cards, and company identification cards. Typically, polymeric data carrying devices include a polymeric substrate, on which information, such as a person's name, account number, address, or picture, is imprinted. After the polymeric substrate is customized, the card is typically protected with a clear protective overlay.
Typical protective overlays include a resin such as methyl methacrylate, ethyl methacrylate, vinyl chloride/vinyl acetates, cellulose acetate butyrates and other similar resins. The protective overlay may be applied to the polymeric substrate as a wet lacquer by dissolving the resin in a solvent or carrier. After the lacquer is applied to the substrate, the solvent or carrier is evaporated and the residual resin forms the protective overlay.
Alternately, the protective overlay can be applied to the polymeric substrate as a laminate. In this technique, the resin is first applied to a carrer such as polyester film. To evenly disperse the resin on the film, the protective resin is typically dissolved in a solvent or carrier solution and coated onto the film using a solution coating machine, such as a machine for gravure printing, mayer rod metering, reverse roll, slot die, curtain coating or screen printing. After the solution is applied to the film, the solvent or carrier solution is evaporated, typically by the application of heat. Similarly, a resinous heat sealable adhesive, such as butyl methacrylate or vinyl chloride/vinyl acetate polymers, is coated on top of the protective coating. The resultant protective laminate can then be laminated to the polymeric substrate with the application of heat and pressure. After lamination, the carrier film is stripped away, leaving a protective coating on the card surface which protects images thereon from abrasion, solvent or plasticiser attack.
Other protective laminates include clear films such as polyester, polypropylene, polyvinyl chloride, acetate, etc. that can be laminated to the surfaces of the card. According to this technique, a solution including a heat sealable adhesive is coated onto the clear film. The solvent is evaporated to leave an adhesive layer on the clear film. The film is then die cut to the desired dimensions and hot laminated to the card using a hot roller or hot platen.
Other known protective coatings for data carrying devices include ultraviolet radiation curable ("U.N. curable") compositions. U.V. curable compositions include monomers and/or oligomers that polymerize upon exposure to U.V. radiation. U.V. curable coatings are generally applied to a data carrying device as a flowable composition and subsequently cured to form a protective coating. U.V. cured protective coatings provide superior abrasion and chemical resistance as compared to other resinous protective coatings due to cross-linking of the monomers and/or oligomers in the coating induced by exposure to U.V. radiation.
However, there are disadvantages associated with U.V. curable compositions. The U.V. curable composition must be exposed to U.N. radiation, thus an end user risks exposure to U.V. radiation. Furthermore, the equipment necessary for curing a U.V. curable composition is both expensive and complex.
A protective coating for data carrying devices that has the superior physical properties of U.V. curable coatings without the disadvantages associated therewith is therefore desirable. It is filrther desirable to have a protective coating that can be applied to a data carrying device by an unskilled end user without significant exposure to hazardous chemicals or need for complex machinery.